Serological and vaccine evaluation for hepatitis B among Community Health Workers

Abstract Objective: to identify the vaccination and serological status against hepatitis B among community health workers; to vaccinate against hepatitis B virus and to evaluate the immune response of susceptible workers. Method: phase I, cross-sectional and descriptive study, among community health workers in a capital city of the Midwest region, through a self-administered questionnaire, checking of vaccination cards, and blood collection for testing of serological markers for hepatitis B. Phase II, cohort study carried out in vaccinated non-immune workers identified in phase I. They received one dose of vaccine (challenge dose) and serological testing. Results: a total of 109 workers participated in the study. Most had vaccination record (97; 89.0%) and vaccination completeness (75; 77.3%), while the isolated anti-HBs (Antibodies against hepatitis B virus) marker was detected in 78 (71.6%) workers. The prevalence of hepatitis B virus exposure was 8.2%. Of the ten non-immune vaccinated workers, after challenge dose, one remained susceptible. Conclusion: although most workers are vaccinated and show immunological response to hepatitis B, susceptibility after challenge dose was identified. Therefore, it is necessary to have a surveillance program of the vaccination situation and serological status for this virus, to promote these workers’ safety.


Introduction
Community Health Workers (CHWs) make up the multi-professional health team in many countries around the world (1) . The International Labor Organization defines CHWs as professionals who provide care to the population through "referral and follow-up, case management, basic preventive health services, and home visiting services to specific communities" (2) .
In performing their work activities, these workers are exposed to risks, including exposure to biological material (3) , and the hepatitis B virus (HBV) is of epidemiological importance for this group (4) . In 2019, approximately 296 million people were chronic carriers of the HBV (5) and in some groups, such as health care workers (HCWs), the prevalence was higher (6) .
It is known that vaccination is the main preventive measure against HBV, therefore, the Brazilian National Immunization Program, since 1993, has made the vaccine available for free for all HCWs with a schedule of three doses at intervals of zero, one and six months (7) .
For HCWs, in addition to vaccination, international and national organizations recommend a test to confirm the vaccine-induced immune response, the antibodies to hepatitis B virus surface antigen (anti-HBs), 30 to 60 days after completion of the vaccination schedule (12)(13)(14)(15)(16) .
The cost of implementing testing for anti-HBs after completion of the regimen is low compared to postexposure prophylactic management of HBV (19) . In addition, health care facilities that jointly adopt anti-HBs testing in surveillance programs and the vaccine have higher HCW vaccination coverage than facilities that do not offer the test (20) . And this ensures greater safety for the execution of the labor activities of these workers.
Regarding CHWs, there is still a gap in knowledge about HBV-related health conditions among these workers, who have been working in primary care since 1991.
Worldwide, there are also few studies conducted with this professional category. Thus, knowing the vaccination and serological status of CHWs against HBV allows the development of protection strategies for these workers exposed to this virus.  (22) . Currently, Goiânia has 62 FHC, divided into seven Health Districts with 896 CHWs (23) .
This study was conducted in the Western Health District whose region, according to the Primary Care

Study period and population
The cross-sectional study was conducted from July to December 2019 and the cohort from January to May 2020.
In phase I, CHWs aged 18 years or older were included and those who were on vacation and/or leave on the scheduled dates were excluded. Therefore, of the 172 CHWs, 36 were on vacation or leave and were excluded from the study. The inclusion criteria for the cohort (phase II) were: CHWs who had three doses of the hepatitis B vaccine and anti-HBs titers <10 mIU/mL in the serological test. Individuals in this situation were eligible to receive the challenge dose (12) .  The test results were personally delivered to each CHW. Those who were not vaccinated or had an incomplete schedule were oriented to take a new three-dose schedule or to complete the schedule (12,16) . Individuals who did not present protective anti-HBs titers were referred to the public health care network and oriented to continue hepatitis B vaccination.

Study variables
The variables investigated in this study were: sex;

Since the introduction of the hepatitis B vaccine in
Brazil in 1998, the epidemiological profile of HBV has been undergoing changes. Currently, a low prevalence for hepatitis B is found among the general population of the country (25) . On the other hand, some groups, such as CHWs, remain at risk for infection, considering their exposure characteristics and low vaccination rates.
In this study, an HBV exposure rate of 8.2% (95% CI= 4.4%-15.5%) was found and the age of exposed   Brazil for healthcare professionals since 1993 (7) . Moreover, more than 90% of the participants joined the service less than 20 years ago.

No studies investigating vaccination coverage among
CHWs through vaccination cards were identified in the literature consulted. Among the studies that showed vaccination rates reported by CHWs working in Primary Health Care through questionnaires, the percentages of vaccinated CHWs were below the value found in this study, 41.0% (31) , 65,4% (32) ; however, in another study (8) , virus (34) . In an investigation on the profile of accidents with exposure to biological material that occurred in the southern region of the state of Minas Gerais, it was found that five CHWs (1.1%) had suffered accidents, among whom two had not been vaccinated against hepatitis B (27) . The chance of susceptible individuals contracting the virus ranges from 6%-30.0% (35) , thus, the possibility of seroconversion is a reality present in the CHWs' work activities and may go unnoticed.
The age of the susceptible individuals ranged from 31 to 60 years. It can seen that some of these CHWs were born before the vaccine was implemented in the country (7) .
However, the availability of the vaccine for free for over 20 years in the Unified Health System (UHS) for HCWs reveals the missed opportunities for vaccination among these workers, especially since they work in FHCs that have vaccine rooms as one of the essential environments in the unit's structure (36) .
Ten participants showed a vaccination card with a record of three doses of vaccine administration, but did International and national recommendations call for anti-HBs testing ideally 30 to 60 days after the completion of the vaccination schedule (12,16) (20) . Thus, a labor monitoring policy may contribute to the prevention and control of hepatitis B.
In this study, hepatitis B vaccine non-responder status was not assessed. Two complete vaccination schedules followed by anti-HBs titers less than or equal to 10 mIU/mL within 30 to 60 days after completion of vaccination are required to confer vaccine non-responder status (12) . It is known that intrinsic, extrinsic, perinatal, environmental, behavioral, nutritional, vaccine and administration factors (37) can affect the immunogenicity of an individual. it was not possible to obtain a photocopy of the vaccination card of all study participants, for those who did not present the card, we searched the National Immunization Program Information System in order to obtain information about the vaccination schedule of each worker.

Conclusion
In the evaluation of CHWs in work activities, it was